Vinylidene fluoride-based resin multi-layered film

Abstract

Disclosed is a vinylidene fluoride-based resin multi-layered film including two layers composed of a front surface layer laminated on a rear surface layer, in which the front surface layer contains 80% by mass or more of a vinylidene fluoride-based resin and 20% by mass or less of a methacrylic acid ester-based resin, the degree of crystallization of the front surface layer is 45% or higher, the ratio occupied by α-crystals in the entire crystal component of the vinylidene fluoride-based resin is 60% or higher, the thickness of the front surface layer is 15 μm or more, and the rear surface layer contains 90% by mass or more of a methacrylic acid ester-based resin.

The invention claimed is: 
     
       1. A vinylidene fluoride-based resin multi-layered film including two layers composed of a front surface layer laminated on a rear surface layer,
 wherein the front surface layer contains 80% by mass or more of a vinylidene fluoride-based resin and 20% by mass or less of a methacrylic acid ester-based resin, the degree of crystallization of the front surface layer is 45% or higher, the ratio occupied by α-crystals in the entire crystal component of the vinylidene fluoride-based resin is 60% or higher, the thickness of the front surface layer is 15 μm or more, and 
 the rear surface layer contains 90% by mass or more of a methacrylic acid ester-based resin. 
 
     
     
       2. The vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein when a white thermoplastic resin layer is laminated immediately beneath the rear surface layer, and in a state in which the thermoplastic resin layer has been heated to 80° C., 500 μl of an acidic aqueous solution at pH 1 is dropped on the front surface layer side, the change in the degree of yellowness, Δb, after 3 hours and 30 minutes is 2 or less. 
     
     
       3. The vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein when a white thermoplastic resin layer containing a hindered amine-based light stabilizer is laminated immediately beneath the rear surface layer, and the thermoplastic resin layer is put in a dark place in an environment at 80° C. for 600 hours, the change in the degree of yellowness, Δb, is 2 or less. 
     
     
       4. The vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein the vinylidene fluoride-based resin contains a copolymer of vinylidene fluoride and hexafluoropropene and/or polyvinylidene fluoride. 
     
     
       5. The vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein the rear surface layer contains 10% by mass or less of a vinylidene fluoride-based resin. 
     
     
       6. The vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein the rear surface layer contains a triazine-based ultraviolet absorber in an amount of 0.01% to 10% by mass. 
     
     
       7. The vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein the total thickness including the front surface layer and the rear surface layer is 20 to 200 μm. 
     
     
       8. The vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein the vinylidene fluoride-based resin multi-layered film is laminated on a decorative film. 
     
     
       9. A decorative film comprising the vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein the multi-layered film comprises a decorative layer laminated on the rear surface layer. 
     
     
       10. A car or an automotive part, having the decorative film according to  claim 9  adhered to a surface of the car or automotive part. 
     
     
       11. The vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein the multi-layered film comprises a decorative layer laminated on the rear surface layer and comprising a hindered amine-based light stabilizer. 
     
     
       12. The vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein the multi-layered film consists of the front surface layer and the rear surface layer. 
     
     
       13. The vinylidene fluoride-based resin multi-layered film according to  claim 1 , wherein the multi-layered film is produced by a method comprising molding a resin composition by melt extrusion by utilizing a T-type die, and the amount of conversive heat per unit time at the time of cooling the molten resin is 70 to 180 KW per kg of the molten resin according to a calculation formula represented by the following formula:
   amount of conversive heat=specific heat (J/kg·° C.) of resin composition×Δ T /cooling time (sec),
 
 where ΔT=temperature of molten resin−temperature after cooling. 
 
     
     
       14. A method of producing the multi-layered film according to  claim 1 , the method comprising molding a resin composition by melt extrusion by utilizing a T-type die, wherein the amount of conversive heat per unit time at the time of cooling the molten resin is 70 to 180 KW per kg of the molten resin according to a calculation formula represented by the following formula:
   amount of conversive heat=specific heat (J/kg·° C.) of resin composition×Δ T /cooling time (sec),
 
 where ΔT=temperature of molten resin−temperature after cooling. 
 
     
     
       15. The method of  claim 14 , wherein the molding of the resin composition by melt extrusion comprises the steps of:
 disposing a metal cooling roll and a rubber roll under a T-type die; 
 extruding the molten resin through a lip port of the T-type die; 
 pinching the extruded resin between the metal cooling roll and the rubber roll; 
 and solidifying the resin by cooling.